Moons – Facts about the Moons of the Solar System

The solar system is a busy place with more than 194 known moons orbiting the planets and dwarf planets. The two most common types of moons are called natural satellites, meaning they were formed from rock that circled around their parent body due to gravity. Just like how our own Moon orbits Earth! Did you know that four of the 13 planets and dwarf planets in our solar system don’t have any moons? These are Mercury and Venus, and the dwarf planets Ceres and Makemake. In this article, we’ll find out the number of moons each planet has and their names.

Terrestrial Planet Moons
Earth, Mars
Gas Giant Moons
Jupiter, Saturn, Uranus, Neptune
Dwarf Planet Moons
Pluto, Haumea, Makemake, Eris

The Moon (Earth’s Moon)

The Earth has one solitary moon that we call the Moon and occasionally Luna.

MoonDiscoveredDiscovererDistance from Planet (km)Diameter (km)Orbital Period (days)
Moon (Luna)Galileo1609384,4003,47527.322

Mar’s Moons

Mars’ two moons, Phobos and Deimos were discovered in 1877 by astronomer Asaph Hall. He named them for the Latin terms “fear” and “panic” after their discovery caused panic among astrologers because they had been overlooked up until that point. These tiny natural satellites are some of the smallest natural satellites. They are thought to be captured asteroids which makes them all the more intriguing.

MoonDiscoveredDiscovererDistance from Planet (km)Diameter (km)Orbital Period (days)
Deimos1877Asaph Hall23,46012.41.2624
Phobos1877Asaph Hall9,27022.50.3189

Jupiter’s Moons

Jupiter has at least 79 moons in orbit around it, the second largest number of natural satellites. Jupiter’s 4 most sizable moons Ganymede, Callisto, Io, and Europa are known as the Galilean Moons because they were also observed by astronomer Simon Marius alongside their discoverer Galileo Galilei – all who happened to be alive at about the same time!

MoonDiscoveredDiscovererDistance from Planet (km)Diameter (km)Orbital Period (days)
Adrastea1979Jewitt & Danielson128,98026×160.298
Aitne2001S. Sheppard, D. Jewitt, & J. Kleyna23,547,0003736
Amalthea1892E. Barnard181,300262 x1340.498
Ananke1951S. Nicholson21,200,00020631
Aoede203S. Sheppard, D. Jewitt, & J. Kleyna23,807,6554748.8
Arche2002S. Sheppard23,064,0003715.6
Autonoe2001S. Sheppard, D. Jewitt, & J. Kleyna24,122,0004753
Carme1938S. Nicholson22,600,00030692
Callirrhoe2000Spacewatch Project Minor Planet Center24,200,00010774
Carpo2003S. Sheppard, D. Jewitt, & J. Kleyna17,100,0003456.5
Chaldene2000S. Sheppard, D. Jewitt, Y. Fernandez, & G. Magnier23,179,0003.8741
Cyllene2003S. Sheppard, D. Jewitt, & J. Kleyna24,000,0002737.80
Elara1905C. Perrine11,737,00080259.65
Erinome200S. Sheppard, D. Jewitt, Y. Fernandez, & G. Magnier23,279,0003.2672
Euanthe2001S. Sheppard, D. Jewitt, & J. Kleyna21,017,0003622
Eukelade2003S. Sheppard, D. Jewitt, & J. Kleyna24,557,2954746.4
Euporie2001S. Sheppard, D. Jewitt, & J. Kleyna19,394,0002534
Eurydome2001S. Sheppard, D. Jewitt, & J. Kleyna23,219,0003713
Harpalyke2000S. Sheppard, D. Jewitt, Y. Fernandez, & G. Magnier21,105,0004.3595
Hegemone2003S. Sheppard, D. Jewitt, & J. Kleyna24,514,0953781.6
Helike2003S. Sheppard, D. Jewitt, & J. Kleyna10,972,8304233.8
Hermippe2001S. Sheppard, D. Jewitt, & J. Kleyna21,252,0004630
Himalia1904C. Perrine11,480,000170250.57
Iocaste2000S. Sheppard, D. Jewitt, Y. Fernandez, & G. Magnier21,269,0005.2657
Isonone2000S. Sheppard, D. Jewitt, Y. Fernandez, & G. Magnier23,217,0003.8712
Kale2001S. Sheppard, D. Jewitt, & J. Kleyna23,124,0002609
Kallichore2003S. Sheppard, D. Jewitt, & J. Kleyna22,395,3902683
Kalyke2000S. Sheppard, D. Jewitt, Y. Fernandez, & G. Magnier23,583,0005.2760
Kore2003S. Sheppard, D. Jewitt, & J. Kleyna24,543,0002779.2
Leda1974C. Kowal11,094,00010238.72
Lysithea1938S. Nicholson11,720,00024259.22
Magaclite2000S. Sheppard, D. Jewitt, Y. Fernandez, & G. Magnier23,806,0005.4771
Metis1979S. Sunnott127,960400.295
Mneme2003Scott S. Sheppard & B. Gladman21,069,0002620.04
Orthosie2001S. Sheppard, D. Jewitt, & J. Kleyna21,168,0002617
Pasiphae1908P. Melotte23,500,00036735
Pasithee2001S. Sheppard, D. Jewitt, & J. Kleyna23,029,0002715
Praxidike2000S. Sheppard, D. Jewitt, Y. Fernandez, & G. Magnier21,147,0006.8632
Sinope1914S. Nicholson23,700,70028758
Sponde2001S. Sheppard, D. Jewitt, & J. Kleyna23,808,0002732
S/2000 J112000S. Sheppard, D. Jewitt, Y. Fernandez, & G. Magnier12,555,0004.0284.3
S/2003 J22003S. Sheppard, D. Jewitt, & J. Kleyna28,570,4102982.50
S/2003 J32003S. Sheppard, D. Jewitt, & J. Kleyna18,339,8852504
S/2003 J42003S. Sheppard, D. Jewitt, & J. Kleyna23,257,9202723.2
S/2003 J52003S. Sheppard, D. Jewitt, & J. Kleyna24,084,1804759.7
S/2003 J92003S. Sheppard, D. Jewitt, & J. Kleyna22,441,6801683
S/2003 J102003S. Sheppard, D. Jewitt, & J. Kleyna24,249,6002767
S/2003 J122003S. Sheppard, D. Jewitt, & J. Kleyna19,002,4801533.3
S/2003 J152003S. Sheppard, D. Jewitt, & J. Kleyna22,000,0002668.4
S/2003 J162003S. Sheppard, D. Jewitt, & J. Kleyna21,000,0002595.4
S/2003 J172003S. Sheppard, D. Jewitt, & J. Kleyna22,000,0002690.3
S/2003 J182003S. Sheppard, D. Jewitt, & J. Kleyna20,700,0002606.3
S/2003 J192003S. Sheppard, D. Jewitt, & J. Kleyna22,800,0002701.3
S/2003 J 232003S. Sheppard, D. Jewitt, & J. Kleyna23,563,0002732.44
S/2010 J 12010S. Sheppard, D. Jewitt, & J. Kleyna23,314,3352582.22
S/2010 J 22010Veillet20,307,1501725.06
S/2011 J 22011S. Sheppard, D. Jewitt, & J. Kleyna23,329,7101288.82
S/2011 J 12011Jacobson et al.20,155,2901724.34
Taygete2000S. Sheppard, D. Jewitt, Y. Fernandez, & G. Magnier23,360,0005.0687
Thebe1979S. Synnott221,9001000.675
Thelxinoe2003Scott S. Sheppard & B. Gladman21,162,0002628.09
Themisto1975C. Kowal & E. Roemer7,507,0008130.07
Thyone2001S. Sheppard, D. Jewitt, & J. Kleyna21,312,0004615

Saturn’s Moons

Saturn’s ring system is famous for being one of the most unique formations in our solar system. What many people don’t know, however, are Saturn’s other secrets–namely its 81 moons! From tiny worlds to a spherical moon such as Titan these outer satellites play an important role in shaping and maintaining this heavenly body. Saturn’s moons range from irregular worlds to ellipsoidal. The first of Saturn’s moons observed was Titan in 1655 by Christiaan Huygens, another moon wasn’t found until 1671 when Giovanni Domenico Cassini discovered Iapetus. Two of Saturn’s own satellites (Janus & Epimetheus) swap orbits every 4 years!

MoonDiscoveredDiscovererDistance from Planet (km)Diameter (km)Orbital Period (days)
Aegir2005D. Jewitt, S. Sheppard, J. Kleyna20,735,00061,116.5
Albiorix2000Gladman et al.16,392,00030783
Anthe2004Cassini Imaging Team197,70011.04
Atlas1980R. Terrile137,64037×270.602
Bebhionn2005D. Jewitt, S. Sheppard, J. Kleyna17,119,0006834.8
Bergelmir2005D. Jewitt, S. Sheppard, J. Kleyna19,338,00061,005.9
Bestla2005D. Jewitt, S. Sheppard, J. Kleyna20,129,00071,083.6
Calypso1980B. Smith294,66030×161.888
Daphnis2005Cassini Imaging Science Team136,50070.594
Dione1684G. Cassini377,40011202.737
Enceladus1789W. Herschel238,0204981.370
Epimetheus1966R. Walker151,422138×1100.694
Erriapo2000Intl. Team of 8 Astronomers17,611,00010871.17
Farbauti2005D. Jewitt, S. Sheppard, J. Kleyna20,390,00051,086.1
Fenrir2005D. Jewitt, S. Sheppard, J. Kleyna22,453,00041,260.3
Fornjot2005D. Jewitt, S. Sheppard, J. Kleyna25,108,00061,490.9
Greip2006S. Sheppard, D. Jewitt, J. Kleyna18,206,0006921.2
Hati2005D. Jewitt, S. Sheppard, J. Kleyna19,856,00061,0.38.7
Helene2005Laques & Lecacheux377,40036×282.737
Hyperion1980W. Bond1,481,000360×22621.277
Hyrokkin1848S. Sheppard, D. Jewitt, J. Kleyna18,437,0008931.8
Iapetus1671G. Cassini3,561,300143679.3215
Ijiraq2000Intl. Team of 8 Astronomers11,440,00014451.48
Janus1966A. Dollfus151,472190×1540.695
Jarnsaxa2006S. Sheppard, D. Jewitt, J. Kleyna18,811,0006964.7
Kari2006S. Sheppard, D. Jewitt, J. Kleyna22,118,00071,233.6
Kiviuq2000Intl. Team of 8 Astronomers11,365,00017449.22
Loge2006S. Sheppard, D. Jewitt, J. Kleyna23,065,00061,312
Methone2004C.C. Porco et al./Cassini194,00031.01
Mimas1789W. Herschel185,5203980.942
Mundilfari2000Intl. Team of 8 Astronomers18,709,0007951.38
Narvi2003Scott S. Sheppard, David Jewitt, and Jan Kleyna18,719,0008956.2
Paaliaq2000Intl. Team of 8 Astronomers15,199,00025686.92
Pallene2004C.C. Porco et al./Cassini211,00041.14
Pan1990M. Showalter133,63019.320.5750
Pandora1980S. Collins141,700110×620.629
Phoebe1898W. Pickering12,952,000220550.48
Polydeuces2004C.C. Porco et al./Cassini377,40042.74
Prometheus1980S. Collins139,350148×680.613
Rhea1672G. Cassini527,04015284.518
Siarnaq2000Intl. Team of 8 Astronomers18,160,00045893.07
Skathi2000Intl. Team of 8 Astronomers15,645,0008728.93
Skoll2006S. Sheppard, D. Jewitt, J. Kleyna17,665,0006878.3
Surtur2006S. Sheppard, D. Jewitt, J. Kleyna22,707,00061,297.7
Suttungr2000Gladman et al.19,470,00071,016.8
S/2004 S072004D. Jewitt, S. Sheppard, J. Kleyna19,800,00061,103
S/2004 S122004D. Jewitt, S. Sheppard, J. Kleyna19,650,00051,048
S/2004 S132004D. Jewitt, S. Sheppard, J. Kleyna18,450,0006906
S/2004 S172004D. Jewitt, S. Sheppard, J. Kleyna18,600,0004986
S/2006 S12006S. Sheppard, D. Jewitt, J. Kleyna18,981,1356970
S/2006 S32006S. Sheppard, D. Jewitt, J. Kleyna21,132,00061,142
S/2007 S22007S. Sheppard, D. Jewitt, J. Kleyna16,560,0006800
S/2007 S32007S. Sheppard, D. Jewitt, J. Kleyna20,518,50051,100
Tarqeq2007S. Sheppard, D. Jewitt, J. Kleyna18,009,0007887.50
Tarvos2000Intl. Team of 8 Astronomers18,239,00016925.70
Telesto1980B. Smith294,66030×161.888
Tethys1684G. Cassini294,66010601.888
Thrymr2000Intl. Team of 8 Astronomers20,470,00071088.89
Titan1655C. Huygens1,221,850515015.945
Ymir2000Intl. Team of 8 Astronomers23,096,000201312.37

Uranus’ Moons

Uranus is home to 27 moons that orbit the planet. The five largest are named Puck, Miranda, Ariel, Umbriel, and Titania. These large satellites each have their own unique characteristics but share some similarities in shape with Uranus’s thin rings. Discovered by William Herschel in 1781, the largest two moons of Uranus are Titania and Oberon. They were observed as part of his mission to discover more planets than anyone else. Which he did with a total tally of 13! The four other large moons show signs that they too have an internal activity shaping their surfaces.

MoonDiscoveredDiscovererDistance from Planet (km)Diameter (km)Orbital Period (days)
Ariel1851W. Lassell191,24011602.520
Belinda1986Voyager 275,260660.624
Bianca1986Voyager 275,260420.433
Caliban1997Gladman, Nicholson, Burns, & Kavelaars7,200,00080579.50
Cordelia1986Voyager 249,750260.335
Cressida1986Voyager 261,770620.464
Cupid2003M. Showalter & J. Lissauer74,800120.618
Desdemona1986Voyager 262,660540.474
Ferdinand2001M. Holman & B. Gladman et al20,901,000212,823.4
Francisco2001M. Holman & B. Gladman et al4,276,00022266.6
Juliet1986Voyager 264,360840.493
Mab2003M. Showalter & J. Lissauer97,734160.923
Margaret2003S. Sheppard14,688,700111,694.8
Miranda1948G. Kuiper129,7804721.414
Oberon1787W. Herschel582,600152613.463
Ophelia1986Voyager 253,44030.40.3764
Perdita1986E. Karkoschka/Voyager 276,420200.638
Portia1986Voyager 266,0851080.531
Prospero1999Kavelaars, Gladman, Holman et al16,256,000305.346
Puck1985Voyager 286,0101540.762
Rosalind1986Voyager 269,941540.558
Setebos1999Kavelaars, Gladman, Holman et al17,418,000472,234.8
Stephano1999Kavelaars, Gladman, Holman et al8,004,00032677.4
Sycorax1997Gladman, Nicholson, Burns, & Kavelaars12,200,0001601283.39
Titania1787W. Herschel435,8401,5788.706
Trinculo2001M. Holman, J. Kavelaars & D. Milisavljevic8,578,00010759
Umbriel1851W. Lassel265,97011904.144

Neptune’s Moons

Neptune has at least 14 moons and the largest of these, Triton was discovered by William Lassell in 1846 one day after the discovery of Neptune. It wasn’t until over 100 years later before a second moon would be found circling around this planet. The most distant Moon, Neso takes 26 years to make one trip around Neptune!

MoonDiscoveredDiscovererDistance from Planet (km)Diameter (km)Orbital Period (days)
Despina1989Voyager 262,0001600.40
Galatea1989Voyager 252,5001400.33
Halimede2002M. Holman & J.J. Kavelaars15,686,000601,874.83
Larissa1989Voyager 273,6002000.56
Laomedeia2002M. Holman & J.J. Kavelaars22,613,200382,980.4
Naiad1989Voyager 248,200500.30
Nereid1949G. Kuiper5,513,400340360.16
Neso2002Holman & Gladman et al47,279,670609,007.1
Proteus1989Voyager 2117,6004201.12
Psamathe2003D. Jewitt, J. Kleyna & S. Sheppard46,738,000389,136.11
Sao2002M. Holman & J.J. Kavelaars22,337,190382,925.+
Thalassa1989Voyager 250,000900.31
Triton1846W. Lassel354,80027055.877
S/2004 N 12013Showalter, M. R. et al.105,30016-200.936

Pluto’s Moons

There are four smaller moons of Pluto: Hydra, Nyx, Styx, and Kerberos. They lie out beyond Charon Pluto’s fifth moon and were discovered using the Hubble Space Telescope on May 15th, 2005. These moons rotate chaotically on their axes so they’re likely to have been created during a giant collision that scattered them into orbit around Pluto and Charon.

MoonDiscoveredDiscovererDistance from Planet (km)Diameter (km)Orbital Period (days)
Charon1978J. Christy19,5711,2076.387
Nix2005H.A. Weaver, S.A. Stern, et al.48,67544-13024.856
Hydra2005H.A. Weaver, S.A. Stern, et al.64,78044-13038.206
Kerberos2011Showalter, M. R. et al.59,00013-3432.1
Styx2012Showalter, M. R. et al.42,00010-2520.2

Haumea’s Moons

The two moons of Haumea were discovered in 2005 from observations made by the W. M. Keck Observatory, and they are called Hi’iaka (the smaller one) and Namaka (the larger one).

MoonDiscoveredDiscovererDistance from Planet (km)Diameter (km)Orbital Period (days)
Namaka2005H.A. Weaver, S.A. Stern, et al.~39,000~17034.7
Hi’iaka2005H.A. Weaver, S.A. Stern, et al.49,500~31049.12

Makemake’s Moon

The moon of the dwarf planet Makemake was discovered in April 2016 by observations made with a telescope called Hubble.

MoonDiscoveredDiscovererDistance from Planet (km)Diameter (km)Orbital Period (days)
S/2015 (136472) 12005Michael E. Brown20,92117512

Eris’ Moon

Eris’s only known moon was discovered in 2005 by Mike Brown and the adaptive optics team at the W. M. Keck Observatory to their delight!

MoonDiscoveredDiscovererDistance from Planet (km)Diameter (km)Orbital Period (days)
Dysnomia2005M. Brown, M. van Dam, A. Bouches, D. Le Mignant30,000-36,000~300~14